Watersheds

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Transcript of Watersheds

Watersheds Watershed: The land area that supplies water to a river system. Just as a city, county or state has boundaries, so does a watershed. A divide represents the boundary of a watershed. Think of this as a line that connects all the highest points in an area. Watersheds tie in to the entire water system because they directsurface water and absorb ground water. ground water Surface water is water collecting on the ground or in a stream, river, lake, pond, etc. Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of rocksGroundwater is recharged from, and eventually flows to, the surface naturally; natural discharge often occurs springs and can form wetlands.Groundwater is also often withdrawn for farming and industrial use by wells. SO...what effects do we make on the groundwater or surface water in our watersheds? Surface Water Evaporation is when the sun heats up water in rivers or lakes or the ocean and turns it into vapor or steam. The water vapor or steam leaves the river, lake or ocean and goes into the air. This means that heat energy is used from the surrounding area. Transpiration is the process by which plants lose water out of their leaves. Transpiration gives evaporation a bit of a hand in getting the water vapor back up into the air. Water vapor in the air gets cold and changes back into liquid, forming clouds. This is called condensation. Precipitation occurs when so much water has condensed that the air cannot hold it anymore. The clouds get heavy and water falls back to the earth in the form of rain, hail, sleet or snow. Collection: When water falls back to earth as precipitation, it may fall back in the oceans, lakes or rivers or it may end up on land. When it ends up on land, it will either soak into the earth and become part of the “ground water” that plants and animals use to drink or it may run over the soil and collect in the oceans, lakes or rivers where the cycle starts The water cycle is vital for our planet:

the water cycle purifies waterreplenishes the land with freshwatertransports minerals to different parts of the globeIt is also involved in reshaping the geological features of the Earth, through such processes as erosion and sedimentation as the water cycle also involves heat exchange, it exerts an influence on climate as well. Condensation You can see the same sort of thing at home... pour a glass of cold water on a hot day and watch what happens. Water forms on the outside of the glass. That water didn't somehow leak through the glass! It actually came from the air. Water vapor in the warm air, turns back into liquid when it touches the cold glass. It is naturally replenished by precipitation and naturally lost through discharge to evaporation and sub-surface seepage into the groundwater. Surface Water An underground space is called an aquiferwhen it can yield a usable amount of waterfor a community. The depth at which soil pore spaces or fractures and spaces in rock become completely filled with water is called the water table. Pollution, Sediment erosion, sewer leakage, run off, storm water...